Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China.
J Org Chem. 2013 Feb 15;78(4):1354-64. doi: 10.1021/jo302689d. Epub 2013 Jan 29.
A 3-phosphonated N-confused phlorin 3 was synthesized by the reaction of N-confused porphyrin 1 and trimethyl or triethyl phosphite 2 in the presence of acetic acid in good yield. The presence of hydrogen and aryl substituents in one of the meso positions (C5) generates a stereogenic center, resulting in configurationally stable enantiomers. The enantiomers were separated by HPLC and characterized by the circular dichroism method for the first time in the case of phlorin. Further oxidation of 3 by DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) afforded the achiral 3-phosphonated N-confused porphyrin 4. Chiral chlorozinc 4-Zn and chlorocadmium 4-Cd, as well as achiral nickel(II) complexes 4-Ni were also characterized. For 4-Cd in the solid state, formation of a dimer consisting of heterochiral subunits joined by two H-bonds was established by a single crystal X-ray analysis. For 4-Cd, separation of enantiomers was achieved. Slow racemization of 4-Cd in solution prevented the absolute configuration determination by the X-ray method indicating the labile character of the complex. The relationship between circular dichroism and absolute configuration of 3a and 4-Cd was established on the basis of TD-DFT calculations.
一种 3-膦酸化的 N-混淆叶啉 3 通过在乙酸存在下，使 N-混淆卟啉 1 和三甲基或三乙基亚磷酸酯 2 反应，以良好的产率合成。在一个中位（C5）上存在氢和芳基取代基会产生一个手性中心，导致构象稳定的对映异构体。对映异构体通过 HPLC 分离，并首次通过圆二色法在叶啉的情况下进行了表征。进一步用 DDQ（2,3-二氯-5,6-二氰基-1,4-苯醌）氧化 3 得到非手性的 3-膦酸化的 N-混淆卟啉 4。手性氯锌 4-Zn 和氯镉 4-Cd 以及非手性镍（II）配合物 4-Ni 也得到了表征。对于 4-Cd 在固态中，通过单晶 X 射线分析确定了由两个氢键连接的异手性亚基组成的二聚体的形成。对于 4-Cd，实现了对映异构体的分离。4-Cd 在溶液中的缓慢外消旋化阻止了通过 X 射线方法确定绝对构型，表明该配合物不稳定。根据 TD-DFT 计算，建立了 3a 和 4-Cd 的圆二色性与绝对构型之间的关系。
